Aralkyl halide coaccelerator

ABSTRACT

A method of compounding unsaturated elastomers which comprises employing with the elastomer a sulfur-based curing system and a defined aralkyl halide additive. A vulcanizable composition is also disclosed.

United States Patent Bowman 1 Oct. 7, 1975 l l ARALKYL HALIDE COACCELERATOR [58] Field of Search 260/795 8. 783, 784, 785. [75} Inventor: Edward L. Bowman, Alexandria, 260/798 Va. [73] Assignee: Phillips Petroleum Company, [56] Relerences Cned Emmy-mm Okla UNITED STATES PATENTS 2.567,l35 9/l95l Slurgis 260/415 R [22} 2,891,926 6/l959 Doak 260/415 21 Appl. No: 326,32l

Related US Application Data Primary ExaminerChristopher A. Henderson. Jr.

[63] Continuation of Ser. No. 150,233, July 4, I971,

abandoned} [57] ABSTRACT A method of compounding unsaturated elusiomers 260/783; which comprises employing with the elastomer a su|- 260/784; 260/785; 260/798 fur-based curing system and a defined aralkyl halide COBC (308C additive. Avulcanizable composition is also disclosed.

[2 Claims, N0 Drawings ARALKYL HALIDE COACCELERATOR This is a continuation of my application Ser. No. 150,233, filed June 4, 1971 now abandoned.

This invention relates to rubber compounding addi- 2,6-diethylphenyl )(o-ethylphenyl )methane, chloro( 2,- 6-diethylphenyl )phcnylmethanc, chlorodiphenyl-ptolylmethane. chlorodi-l-pyrenylmethane, chlorophcnyl-p-tolylmethane, chlorophenyl-o-tolylmethane,

tives. 5 chlorotriphenylmethane, chlorotril-pyrenylmethane, In one of its more specific aspects, this invention rechlorotri-p-tolylmethane, chlorodi-llates to the use of aralkyl halides in the vulcanization h h l h i d i h w h and the like of rubber. least and mixtures thereof. These materials are used in con- With the increasing use of butadiene-styrene copolycentrations within the range of from about 0.1 to about mer rubbers, there is a continuing need for vulcanizing l l0 phr with best results being Obtained at c0ncemra agents which improve the aging properties of demo tions within the range of from about I to about 4 phr. mers at elevated temperatures. A number of nonsulfur The aforementioned compounds are employed with vulcanizing agents have been, employed some qmte sulfur-based vulcanization systems of the conventional successfully Among 9 whlch have been generally type which include sulfur or compounds which liberate Suggested are the Chlormated my] methyl Compounds sulfur such as dipentamethylene thiuram hexasulfide containing at least one chlorine substituted in the and with Classes of compounds Such as a|dehyde methyl group, for example, benzal chloride a'l amines, guanidines, thiazoles, dithiocarbamates and o'chlombenzomchlorlde bemg proposed m thiuram sulfides which act as vulcanization accelerathe absence of Sulfur m the curing m tors, and with accelerator activators such as zinc oxide, It has now been dlscovcred that certain halogenated litharge, stearic acid, zinc stearate, triethanolamine and afly methyl Compounds w' m the 'l the like. These sulfur-based curing systems can be used l produce surprlsmgly effective re,sults' in conjuction with other conventional compounding ventlon is concerned w th such compounding addltives. materials Such as carbon black According to this i there 15 provided a The aforementioned aralkyl halide additives are emmeihod for .compoundmg. unsaturated elastqmers ployed under conventional conditions of curing time, whlch compnse,s Compoundmg h elastomer a temperature and techniques, which conditions form no sulfurbased curing system and with an aralkyl hallde part ofthe invention when wemployed the use ofthe uddmve havmg the formula aralkyl halide additives act to initially retard cure as R shown by an increase in curing induction time or x scorch time. At longer cure times, they produce a degree of crosslinking which is higher than can be obtained with a conventional cure system, indicating a in wh'ch R Selected from the group conslstmg of more efficient use of sulfur. The cured system is also drogen and an aryl radical having from about 6 to highly resistant to reversion about carbon m one of the R groups being These advantages and unexpected results of the inhydmgem m wh'ch X selecied from the group vention are illustrated in the following examples. In consisting Ofchkmnei bromine and Each R may these examples, the method of this invention will be ilbe alike or the R groups may differ ffOm each other lustrated employing chlorotriphenylmethane and cer- Also according to this invention there is provided 3 Iain other substances. However, the invention is not be vulcanizable composition comprising an elastomer and 40 to be Considered as being limited to the materials a vulcanizing agent comprising a sulfur-based curing ployed system and an aralkyl halide additive as defined above.

This invention is applicable to the curing of what are EXAMPLE I conventionally referred to as highly unsaturated elasto- In a eries of n hl r ph ny n T mers including cis-polyisoprene, natural rubber, emulwas incorporated into three different rubbers in an sion polymerized butadienestyrene copolymers, soluamount of 3 parts by weight per hundred parts by tion polymerized butadiene-styrene copolymers and weight of rubber. Each rubber lacking the inclusion of polybutadiene. the CIPM was also evaluated. The compounds were Example of suitable compounds complying to the prepared by incorporating CTPM in the elastomer foregoing formula are compounds such as bromodistock, adding sulfur and a vulcanization accelerator in phenylmethane, bromodiphenyl-p-tolylmcthanc, conventional amounts. mixing and sheeting off the bromodil -naphthylmethane, bromodi-2,5- stock in a conventional manner. Curing characteristics xylymethane, chlorobis(2,6- of the compounds were determined in a Monsanto diisopropylphenylJmethane, chlorobis(o- Rheometcr at 307F. and physical properties of each of ethylphenylJmethane. chlorobis( m-neopentylphenyl)- the stocks cured for 45 minutes at 307F. were also dephenylmethane, chlorodi-o-cumeny1methane, chloro(- termined. Results were as follows:

TABLE I Monsanto Rhuunlclcr all 307F. (.TPM Scorch, Rubber cone, Max. Vise, (-1 in lhs.) ('un: Rule. No. Rubber '1 ype phr in.-lhs. min. in.-lhs.lmin.

l SBR- l 5H0 n 67 as 0.2 2 SBR ISUU 3 :43 1|: 2.x 3 Natural (J 52 53 3.9 4 3 m 6.2 31 5 High cis-wvlybutatlionc (l 73 9.7 6.4 o 3 7R lull 2H TABLE l-Continued Physical Properties ('ured 45 min. at 3(l7F.

300% (rosslinking Modulus. Heat Buildup Rubber No. \'r psi (AT). F.

I (1.427 I785 75 I 0,452 2375 64 3 0.1% l535 59 4 0.335 l'-)3(l 4h 5 0.47 lll5l) 6i (v 0.4 l 7 l3-l5 56 In the above data. the crosslinking value is a measure of the degree of cure. employing Vr, the volume fraction of polymer in solvent-swollen cured stock as discussed in Rubber World, I35. No. I. 67-73 (I956).

The above data demonstrate that the use of the CT PM results in the production of stocks of slower cure rate and increased scorch time. yet with higher degree of cure in the vulcanized stocks. This is also indicated by the higher modulus and the lower heat buildup for those stocks containing (.TPM.

EXAMPLE ll Samples of a compounded recipe comprised. in parts by weight. of 100 parts natural rubber (No. I smoked sheets). 50 parts carbon black. 2.5 parts sulfur and the usual amounts of zinc oxide. stearic acid, extender oil and accelerator had incorporated in them various quantities of CTPM. The stocks were mixed in the conventional manner and were tested as follows after 45 min. cure at 307F.

TABLE II Stock No. l 3 3 CTPM. phr (I l 2 Tensile. psi 3600 391K) 4000 400'? Modulus. psi 1600 2800 350i! Elongation. .l 5 lt) 515 44 Shore A. Hardness ho (v6 7 Resilience. 3 b2 b3 67 The above data indicate that the addition of CT PM improves certain of the properties of the resulting stocks.

EXAMPLE ll That the additives of this invention produce stocks having a decreased cure rate but an increased modulus. indicating a higher degree of cure is shown by the following data in which solution polymerized butadienestyrene random copolymers and emulsion polymerized butadiene-styrene copolymers were used as the basic rubbers in stocks comprising carbon black. sulfur and other usual ingredients in which CT PM was incorporated in various amounts with the following results:

The above data indicate that the invention is applicable to both solution and emulsion polymerized rubbers.

EXAMPLE lV That the compounds of the present invention benefit from the presence of sulfur and that the effect of the compounds of this invention is greater than the additive effect of the sulfur-containing system and of the aralkyl halide. individually, is shown by the test results of four stocks comprised of natural rubber. Other conventional components were varied only to the extent of the sulfur and CT PM incorporated in them. with the following results:

Table IV Rubber 1 2 3 4 Sulfur. phr U 1.25 2.5 2.5 CTPM. phr 3 3 3 ll Monsanto Rhcomcter Cure Characteristics at 307F.

Max. Vise. in.-lbs. Did b6 80 59 Scorch l5 iIL-lhs.)

min. not 6.5 5.l 4.5

Cure Rate. in.-lbs./

min. cure 2.2 3.7 3.8 Properties. Stocks Cured -15 min. at 307F.

Tensile. psi Did not -l l2ll 3950 3360 300% Modulus.

psi determine J 2450 I750 EXAMPLE V Materials representative of those materials which are the subject of this invention and various chlorinccontaining compounds were incorporated in substantially identical quantities into a butadiene-styrene rubber (SBR-ISOO) stock with carbon black. sulfur and other components normally included in rubber recipes. The resulting stocks were prepared. blended. and tested with the following results:

TABLE V Rubber Number o-chlorochloro- Benzobenzodiphenyl- Additive None CT PM tiichloride trichloridc methane Monsanto Rheomeier Cute Characteristics at JUTF.

Max. Vise. in.-lhs..

60 min. 68 83 I00 70 Scorch (4 in.-lbs. min. 9.7 ll.(l $5 83 11,5 Cure Rate. in.-lhs./min. 4.9 1.4 2.7 4.7 2.8

TABLE V Continued Rubber Number ochlorochloro Benzohcnzotliphenyl- Additive None ('TPM trichloridc trichloritlc methane Properties, Stocks Cured 45 min. at 307F.

Tensilev psi 4075 3550 3890 3230 4200 300% Modulus. psi I425 1650 1695 2660 I275 Elongation, '7? 55(1 48H 530 345 6 It] V X 10', moles/cc LS4 Lhb 1,66 2.22 [.47

A Crossliflk density measured as moles of urusslinks per cc of rubber and calculated from the method of determining Vrl The above results demonstrate that the additives of this invention, that is, additives 2 and 5, produce slow curing but scorch-resistant stocks of good physical properties. The use of benzotrichloride provided a slow curing but scorchy stock while the use of o-chlorobenzotrichloridc produces a faster curing stock than did the use of benzotrichloride but a stock scorchier than that produced in the absence of an additive.

It is evident from the foregoing that various modifications can be made to the method of this invention. However such are considered to be within the scope of the invention.

What is claimed is:

l. A method of vulcanizing a highly unsaturated elastomer which comprises:

a. forming a Composition comprising:

1. a sulfur vulcanizable highly unsaturated elastomer; 2. a sulfur-based curing system; and, 3. an aralkyl halide having the formula wherein R is selected from the group consisting of 6. The method of claim 5 in which said chlorotriphenylmethane is incorporated in said elastomer in an amount of about 3 parts per hundred parts of said elas tomer.

hydrogen and an aryl radical having from about I 6 to about l6 carbon atoms with not more than one of said R groups being hydrogen and b. curing said composition. 2. The method of claim 1 in which said sulfur-based curing system comprises sulfur or compounds of which liberate sulfur.

3. The method of claim 2 in which said aralkyl halide 7. A composition comprising a highly unsaturated vulcanizable elastomer, a sulfur-based curing system and an aralkyl halide having the formula wherein R is selected from the group consisting of hydrogen and an aryl radical having from about 6 to lo carbon atoms with not more than one of said R groups being hydrogen.

8. The composition of claim 7 in which said aralkyl halide is selected from the group consisting of chlorobis-( lb-diisopropylphenyl )methane, chlorobis( oethylphenyl )methane, chlor0bis-( m-neopentylphenyl phenylmethane, chlorodi-o-cumenylmethane, chloro(- 2.6-diethylphenyl o-ethylphenyl )methantn chloro( 2 6-dicthylphenyl )phenylmethane. chlorodiphcnyl-ptolylmethane, chlorodi'l-pyrcnylmethane, chlorophenyl-p-tolylmethane, chlorophenyl-o-tolylmcthane, chlorotriphenylmethanc, chlorotri-l-pyrenlymethanc, chlorotri-p-tolylmethane, and chlorodil naphthylmethane.

9. The composition of claim 7 in which said aralkyl halide is present in an amount within the range of from about 0. l to about 10 parts per hundred parts by weight of said elastomer.

10. The composition of claim 7 in which said aralkyl halide is chlorotriphenylmethane.

11. The method of claim 5 wherein said elastomer is selected from the group consisting of natural rubber, polyisoprene, butadiene-styrene copolymers, polybutadiene, and butadiene-acrylonitrile copolymers and the sulfur-based curing system comprises sulfur and a vul canization accelerator selected from the group consisting of aldehydeamines, guanidines, thiazoles, dithiocarbamatcs, and thiuram sulfides.

12. The composition of claim 7 wherein said elastomcr is selected from the group consisting of natural rubber, polyisoprene, butadiene-styrene copolymers, polybutadiene. and butadieneacrylonitrile copolymer and the sulfur-based curing system comprises sulfur and a vulcanization accelerator selected from the group consisting of aldehyde-amines. guanidines, thiazoles, dithiocarbamates and thiurum sulfides.

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3,910,863

DA E 3 October 7, 1975 tNVENTOR( 1 Edward L. Bowman it is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown betowi Column 5, line 47, after "compounds" delete "of".

Column 6, line 28, before "16" insert about Signed and Sealed this Arrest:

RUTH C. MASON C. MARSHALL D Alluring Officer ANN unmrmiunvr 0f Iurcnls and Trmlvmurkx 

1. A METHOD OF VULCANIZING A HIGHLY UNSATURATED ELASTOMER WHICH COMPRISES: A. FORMING A COMPOSITION COMPRISING:
 1. A SULFUR VULCANIZABLE HIGHLY UNSARURATED ELASTOMER,
 2. A SULFUR-BASED CURING SYSTEM, AND
 2. a sulfur-based curing system; and,
 2. The method of claim 1 in which said sulfur-based curing system comprises sulfur or compounds of which liberate sulfur.
 3. The method of claim 2 in which said aralkyl halide is incorporated in said composition in an amount within the range of from about 0.1 to about 10 parts by weight per hundred parts by weight of said elastomer.
 3. an aralkyl halide having the formula
 3. AN ARALKYL HALIDE HAVING THE FORMULA
 4. The method of claim 1 in which said aralkyl halide is selected from the group consisting of chlorobis(2,6-diisopropylphenyl)methane, chlorobis(o-ethylphenyl)methane, chlorobis(m-neopentylphenyl)-phenylmethane, chlorodi-o-cumenylmethane, chloro(2,6-diethylphenyl)(o-ethylphenyl)methane, chloro(2,6-diethylphenyl)phenylmethane, chlorodiphenyl-p-tolylmethane, chlorodi-1-pyrenylmethane, chlorophenyl-p-tolylmethane, chlorophenyl-o-tolylmethane, chlorotriphenylmethane, chlorotri-1-pyrenylmethane, chlorotri-p-tolylmethane, and chlorodi-1-naphthylmethane.
 5. The method of claim 4 in which said aralkyl halide comprises chlorotriphenylmethane.
 6. The method of claim 5 in which said chlorotriphenylmethane is incorporated in said elastomer in an amount of about 3 parts per hundred parts of said elastomer.
 7. A composition comprising a highly unsaturated vulcanizable elastomer, a sulfur-based curing system and an aralkyl halide having the formula
 8. The composition of claim 7 in which said aralkyl halide is selected from the group consisting of chlorobis-(2,6-diisopropylphenyl)methane, chlorobis(o-ethylphenyl)methane, chlorobis-(m-neopentylphenyl)phenylmethane, chlorodi-o-cumenylmethane, chloro(2,6-diethylphenyl)(o-ethylphenyl)methane, chloro(2,6-diethylphenyl)phenylmethane, chlorodiphenyl-p-tolylmethane, chlorodi-1-pyrenylmethane, chlorophenyl-p-tolylmethane, chlorophenyl-o-tolylmethane, chlorotriphenylmethane, chlorotri-1-pyrenlymethane, chlorotri-p-tolylmethane, and chlorodi-1-naphthylmethane.
 9. The composition of claim 7 in which said aralkyl halide is present in an amount within the range of from about 0.1 to about 10 parts per hundred parts by weight of said elastomer.
 10. The composition of claim 7 in which said aralkyl halide is chlorotriphenylmethane.
 11. The method of claim 5 wherein said elastomer is selected from the group consisting of natural rubber, polyisoprene, butadiene-styrene copolymers, polybutadiene, and butadiene-acrylonitrile copolymers and the sulfur-based curing system comprises sulfur and a vulcanization accelerator selected from the group consisting of aldehydeamines, guanidines, thiazoles, dithiocarbamates, and thiuram sulfides.
 12. The composition of claim 7 wherein said elastomer is selected from the group consisting of natural rubber, polyisoprene, butadiene-styrene copolymers, polybutadiene, and butadiene-acrylonitrile copolymer and the sulfur-based curing system comprises sulfur and a vulcanization accelerator selected from the group consisting of aldehyde-amines, guanidines, thiazoles, dithiocarbamates, and thiurum sulfides. 